This relates generally to electronic devices and, more particularly, to electronic devices that include microelectromechanical systems (MEMS) devices.
Electronic devices often include MEMS devices. MEMS devices may, for example, be used to form accelerometers, gyroscopes, microphones, and other types of sensors. MEMS devices are sometimes formed by bonding a MEMS structure having a suspended moveable member to a complementary metal-oxide-semiconductor (CMOS) substrate having circuitry for sensing movement of the suspended MEMS structure. For example, the semiconductor substrate may include capacitive sensing electrodes that are configured to gather signals produced by movement of the suspended MEMS structure.
The suspended microstructures in a MEMS device are typically formed using a deep reactive ion etch (DRIE). In many cases, the deep etch process used to form trenches around a suspended MEMS structure will leave behind undesirable surface features such as scalloped sidewalls. The presence of scalloped sidewalls and rough surfaces in a MEMS device can make the device more susceptible to fractures and chipping. If care is not taken, the particles released from impact-induced fractures in the silicon can cause electrical shorts between metal contact pads on the semiconductor substrate.
It would therefore be desirable to be able to provide electronic devices with improved MEMS devices.